The skin forms a barrier between the body and the environment, with one of its principal functions being the protection of the body from invasion by potentially hazardous materials and organisms. The skin's integrity is therefore all important to the continued well-being of the individual, and any breach or rupture represents a threat that must be met by the body in order to protect its continued existence.
Under normal circumstances the body provides mechanisms for healing a rupture or breach to restore the integrity of the skin barrier. The repair process for even minor breaches or ruptures takes a period of time extending from hours and days to weeks; and in some instances, as in ulceration, the breach or rupture may persist for extended periods of time, i.e., months or even years. At all times, whether brief or extended, the potential for invasion by pathogenic organisms or foreign substances continues until new tissue has been generated to fully close the rupture or breach.
The healing process is brought about by complex biological mechanisms generally involving several groups of special cells and proteins. Leukocytes, such as neutrophils and macrophages, crowd the wound site and digest foreign pathogens and debris. Such cells also send out chemical signals that marshal fibroblasts in the wound vicinity and ultimately generate connective structures, principally, collagen, which make up a major portion of the new tissues. Endothelial cells generate new blood capillaries that grow into the reconstructed tissue areas where their presence is necessary to supply nutrients to the newly growing tissue cells and remove catabolic products. As the new capillaries grow, the cells on the margin of the wound simultaneously multiply and grow inwardly. The fibrous tissue arising from this cell growth eventually fills the wound cavity with a network of interlacing threads of collagen which in due time, arrange themselves in firm bands and form the permanent new tissue.
The surface of the wound subsequently is covered by a process of enlargement, flattening, and multiplication of the surface, or epithelial cells at the wounds' edge. These epithelial cells spread as sheets into the wound, beneath the scab. Eventually the proliferating epithelial cell sheets emanating from the wound sides coalesce to cover and close the wound on the outer surface.
All of the above noted healing processes take considerable time. The rate of healing is influenced by the wound's freedom from infection, the general health of the individual, presence of foreign bodies, or the like. Even for healthy individuals with no complications, healing can take a considerable period of time, i.e., days to weeks. In some instances, the healing process can be impaired by constitutional deficiences, or by disease processes, and healing may never effectively take place.
Until such time as at least superficial healing has occurred, the individual remains at risk from continued or new infection. Therefore there is a time/rate related risk factor attendant to all wound situations. The quicker the wound can heal, the sooner the risk is removed. Thus any procedure that can influence the rate of wound healing or favorably influence healing of intractible wounds would be of great value.